@Lazy

@Configuration

@ComponentScan(basePackages = "com.baeldung.lazy")

public class AppConfig {

​

    @Bean

    public Region getRegion(){

        return new Region();

    }

​

    @Bean

    public Country getCountry(){

        return new Country();

    }

}

// By default all beans are eagerly loaded (Beans are automatically initialized on the launch of application)

// Recommended : Use eager loading (Reason : Errors in spring configuration can be identified early if there is any)

// Use case : If there are too many beans that you need to stop loading early to speed up application launching process

// Use Scope : Annotation can be used anywhere you can use "@Bean" or "@Component" annotations

​

@Component

class ClassA {

    // Business Logic

}

​

@Component

@Lazy // THIS IS WHAT IS RESPONSIBLE FOR LAZY LOADING : will only load when any bean of this class is needed

class ClassB {

    @SuppressWarnings("unused")

    private ClassA classA;

    public ClassB(ClassA classA) {

        System.out.println("Some Initialization logic");

        this.classA = classA;

    }

    public void doSomething() { System.out.println("Do Something");}

}

​

@Configuration

@ComponentScan

public class LazyInitializationLauncherApplication {

    public static void main(String[] args) {

        try (var context = 

                new AnnotationConfigApplicationContext

                    (LazyInitializationLauncherApplication.class)) {

            System.out.println("Initialization of context is completed"); // All eager loaded beans are created by this point

            context.getBean(ClassB.class).doSomething();  // Only now the lazy bean of ClassB will be loaded since it was called

​

        }

    }

}